URLs preceded URL: or wrapped in angle-brackets are tolerated. URLs can also
be preceded by URL: and wrapped in angle-brackets.

ldap_is_ldap_url() returns a non-zero value if url looks like an LDAP URL
(as opposed to some other kind of URL). It can be used
as a quick check for an LDAP URL; the ldap_url_parse() function should
be used if a more thorough check is needed.

ldap_url_parse() breaks down an LDAP URL passed in url into its component
pieces. If successful, zero is returned, an LDAP URL description is allocated,
filled in, and ludpp is set to point to it. See RETURN VALUES
for values returned upon error.

ldap_url_parse_nodn() acts just like ldap_url_parse() but does not require dn in the
LDAP URL.

ldap_free_urldesc() should be called to free an LDAP URL description that was
obtained from a call to ldap_url_parse().

ldap_url_search() initiates an asynchronous LDAP search based on the contents of the
url string. This function acts just like ldap_search(3LDAP) except that many search
parameters are pulled out of the URL.

ldap_url_search_s() performs a synchronous LDAP search based on the contents of the
url string. This function acts just like ldap_search_s(3LDAP) except that many search
parameters are pulled out of the URL.

ldap_url_search_st() performs a synchronous LDAP URL search with a specified timeout. This
function acts just like ldap_search_st(3LDAP) except that many search parameters are pulled
out of the URL.

ldap_dns_to_url() locates the LDAP URL associated with a DNS domain name. The
supplied DNS domain name is converted into a distinguished name. The directory
entry specified by that distinguished name is searched for a labeled URI
attribute. If successful then the corresponding LDAP URL is returned. If unsuccessful then
that entry's parent is searched and so on until the target distinguished
name is reduced to only two nameparts. If dns_name is NULL then
the environment variable LOCALDOMAIN is used. If attrs is not NULL then
it is appended to the URL's attribute list. If scope is not
NULL then it overrides the URL's scope. If filter is not NULL
then it is merged with the URL's filter. If an error is encountered
then zero is returned, otherwise a string URL is returned. The caller
should free the returned string if it is non-zero.

ldap_dn_to_url() locates the LDAP URL associated with a distinguished name. The number
of nameparts in the supplied distinguished name must be provided. The specified
directory entry is searched for a labeledURI attribute. If successful then the
LDAP URL is returned. If unsuccessful then that entry's parent is searched and
so on until the target distinguished name is reduced to only two
nameparts. If an error is encountered then zero is returned, otherwise a
string URL is returned. The caller should free the returned string if
it is non-zero.